William g



(No Model.)

W. G. A. BONWILL.

REVOLVING ELECTRIC HAMMER TOOL.

Patented Dec. 13, 1887.

WITNESSES:

Q/g INVENTOR;

MW Q. Ola/Jab.

UNITED STATES PATENT ()FFICE.

WILLIAM G. A. BONWILL, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOB TO THE S. S. WHITE DENTAL MANUFACTURING COMPANY, OF SAME PLACE.

REVOLVING ELECTRIC HAMMER TOOL.

SPECIFICATION forming part of Letters Patent No. 374,580, dated December 13, 1887.

Application filed August 29, 1887. Serial No. Qltkl'lfl. (No model.)

To all whom, it 71mg concern.-

Be it known that 1, WILLIAM G. A. BON- WILL, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Revolving-Hammer Tools; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appcrtains to make and use the same.

-The object of my invention is to improve instruments of the class in which ablow is delivered by a revolving hammer upon a reciprocating tool or tool-holder for the purpose, for instance, of drilling rock, plugging teeth, &c.; and it consists of a revolving hammer driven by electromagnetism.

I show in the accompanying drawings my improvements embodied in a dental plugginginstrumcnt, which is sufficient to illustrate them.

In said drawings, Figure l is a view in elevation of the plugging-instrument; Fig. 2, a similar view at right angles to Fig. 1; Fig. 3, a view from the opposite side to Fig. 2, with a portion of the frame removed to show more clearly the commutator or circuit making and breaking devices; and Fig. 4 is a view of a modification of the revolving electromagnetic hammer devices. 5

A hand-piece casing or tube, A, is fitted with a tool-carrying spindle, B, having slight endwise movement therein, as usual. The front end of said spindle B is fitted by a chuck arrangement, I), for the reception and ready interchange of the operating-tools in a common manner. The butt-end b of said spindle B projects beyond the hand-piece casing or tube A, between the arms or forks A A of the frame of the instrument at its butt-end, and is fitted to be struck a rapid series of blows by a revolving hammer, so as to impart said blows to the operating-tool for drilling, plugging teeth, and similar purposes.

There is nothing new in the parts so far described, and they may be of any approved construction. Mechanically-driven revolving hammers have already been employed, My invention lies in fitting the revolving hammer to he revolved by electromagnetism, to which end I may, and preferably do, employ the followingarrangement.

The armature-shaft O is fitted to revolve in or on bearings between the arms A A, and the armature may consist of a cross-piece of iron, D, fixed on the shaft 0 and carrying the wire-spools E E of the armaturemagnet. The poles e e of said spools are' opposed to a piece of softiron, F, fixed on the nonmagnetic frame or arm A, and rendered magnetic by induction from the revolving magnetic armature when a current of electricity is passing therethrough.

The circuit may be run as follows: From the battery, through the wire 1 to the plate or binding-screw 2, forming part of the metal frame; thence through the shaft to the wire of the spool E, through a suitable wire connection, 3; thence through the wire of said spool E and through the wire of the spool E to the insulated commutator G, and from thence, by the brush 4, to the insulated plate 5, and through the key or switch 6 to binding post or plate 7, and from thence to the battery. By the switch 6 the instrument may be thrown into and out of operation. The commutator or make and break device G may have two fiat sides, gg, and two contact ends, gg, which, as the armatureshaft carrying the commutator revolves, make contact with the brush 4-, which is broken when one of the flat-sides of the commutator comes next to but does not touch the brush.

By the alternate make and break of the circuit by the revolving commutator the magnet or magnets E E of the revolving armature are magnetized and demagnetized, and the fixed soft-iron plate F is made magnetic correspondingly, so as to attract the revolving magnets in a well-understood way, and this revolution is the means of imparting the rapid series of blows to the tool-carrying spindle B. The hammer in this instance is formed by one end or both ends of the armature-plate D being extended to strike as it revolves upon the end of said spindle and thereby impart the desired blows. To make said blows more efiective and distinct, I fit one or both ends of the revolving hammer-plate D with a rolling hammer-projection, f, which, when the blow is struck, rolls over the end of the spindle as the hammer revolves. This rolling hammer projection is not claimed herein, as it forms part of another application by me. I have shown only one end of the hammer-plate D as extended to strike the butt-end of the spindle B a blow once for each rotation of the armature; but both ends of said hammer-plate may be fitted to strike a blow, thus making two blows for each revolution of said hammer, or more, if desired, according to the shape of the revolving hammer. In Fig. 4 I have shown a modification of the hammer, in that the rolling hammer projection is on a pivoted springarm revolving with the armature.

My invention is not limited to details, and many changes and variations may be made without departing from my invention.

In speaking of the tool{ in the claim, it

means either the tool and spindle B in one piece or in separate pieces, both ways being common. The tool is usually separable from the spindle, however, so as to be removed and replaced without removing the shank or spindle and to permit various tool-points to be more readily used. I claim as my invcntion-- The combination, with the tool to be hit a series of blows, of a revolving hammer brought in contact with said tool intermittently as the hammer revolves to strike said blows, and an electro-magnet to rotate said revolving hammer, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

\VM. G. A. BON WILL. Witnesses:

J. A. B. WILLIAMs, R0121. E. GORDON. 

